CA1187402A

CA1187402A - Driving device of the cutting station in a platen press

Info

Publication number: CA1187402A
Application number: CA000425795A
Authority: CA
Inventors: Gregor Schoch
Original assignee: Bobst SA
Current assignee: Bobst Mex SA
Priority date: 1982-04-15
Filing date: 1983-04-13
Publication date: 1985-05-21
Also published as: DE3313790C2; SE8302067L; GB2118090B; GB8308997D0; SE8302067D0; DE3313790A1; IT1171128B; ES8403780A1; ES521461A0; CH652967A5; FR2525144A1; SE448288B; GB2118090A; FR2525144B1; US4466318A; JPS58192793A; IT8312483A0; JPS6158279B2

Abstract

ABSTRACT

A driving apparatus for the cutting station of a platen press comprises four toggle-joints provided with cam rollers each engaging a respective cam. The four toggle-joints are arranged in pairs perpendicularly to the transport direction of the sheets in the machine, the pairs of toggle-joints being located on common axes. In the transport direction of the sheets in the machine one pair of toggle-joints is located between the other pair of toggle-joints. The toggle-joints are mounted on a release device driven by a safety coupling. The cams are mounted on a common shaft provided at its end with a braking mechanism.
Release of the security coupling simultaneously initiates the operating of each release device and of the braking mechanism.

Description

The present invention refers to a driving mechanism for the cutting station of a platen press comprising a lower movable platen, an upper fixed platen and means to actuate th~
lower movable platen.
Such driving mechanism, operating by means of a driving cam and a group of toggle-joints actuating the lower movable platen in an up and down movement are known. They are described in United States Patent Nos. 1,053,566 of February 18, 1913, 2,043,246 of June 9, 1936 and 2,425,040 of August 5 , 1947.
United States Patent 1,053,566 shows the use of a cam located on a shaft outside of the toggle-joint system. In this arrangement, the movement generated by the cam is transferred to the toggle-joint system by means of a lever with cam-rollers.
United States Patent 2,043,246 refers to an arrangement using a cam on the axis of symmetry of the toggle-joint system.
The cam is mounted on a shaft located underneath the lower pivoting points of the toggle joints. A set of levers are connected on one end to each pair of toggle-joints and on the other end to a cam-roller. A guiding device mounted on the axle of the cam-roller ensures the centering and determines the lateral position of the axle of the cam-roller, so that the force is e~ually distributed to the to~gle-joints.
United States Patent 2,425,040 also describes a driving device acting on the lower platen of the press. It shows that the use of a cam with inner grooves controlling the motion of the lower platen is known. In this arrangement/ the movement generated by the cam is transferred to a stirrup linked by a lever to each toggle-joint. Guiding of the lower platen occurs with the help of a central slide~
In the control of the movement of the lower platen, the above-mentioned devices all show interesting characteristics, for instance the possibility of influencing the stroke, the speed and the acceleration of the movement of the lower pla-ten. ~ut all these arrangements use one or several levers mounted between the toggle-joints and the cams, which complicates the geometry of the driving device and increases the danger of an inaccurate movement, because there are more leading points. ~oreover, these construc-tions involve significant loads on the contact surfaces between the cams and their rollers, for the toggle-joints are usually actuated in pairs by means oE one single cam. Furthermore, none of these arrangements is provided with a security device acting directly on the toggle-joints.
The present invention intends to overcome difficulties created by driving systems comprisiny cams and toggle-joints.
The invention provides aplaten press havinga cutting sta-tion, and means to transport sheets through said cutting station and driving apparatus for said cutting station, said driving apparatus comprising: alower movable platen and an upper fixed platen, means to actuate said lower movable platen, and means transporting the sheets through the platen press, said actuating means comprising toygle-joints each having two arms hingedly connected by an axle equipped with acam-roller that is urged into engagement with a cam on a driven shaft,each toggle-joint having upper and lower swivelsat the endsofits armsconnected to themovable lower platen and to a station-ary frame part respectively,said toggle-joints being arranged in

- 2 -~7~2 palrs, each pair of toggle-joints being located on a theoretical axis perpendicular to the direction of :Eorward movement of -the sheets in the platen press, the lower movable platen being urged downwardly by pulling means, and said cams beiny effective upon rotation of said driven shaft to extend said toggle-joints and move said lower platen cyclically upwards in parallel with the upper platen against the force of said pulling means, wherein each lower swivel of the forward pair of toggle-joints is connected to a stationary frame part in the form of bearing which is connected to a release device, said release device being operable to displace said bearings away from said driven shaft and thus disable said Eorward pair of toggle~joints so that the upwards movement of -the forward end of the lower platen is reduced.
An example of execution of the device according to the invention will now be described and by way of example only, with re:Eerence to the accompanying drawings, wherein:
Figure 1 is a general schematical view of a platen press;
Figure 2 is a plan of the cuttin~ station of a platen press;
Figure 3 is a cross sectional view along III-III of Figure 2;
Figure 4 is a cross sectional view along IV-IV of Figure 2;
Figure 5 is a cross sectional view along V-V of Figure 2;

Figure 6 is a cross sectional view along VI-VI of Figure 2; and Figure 7 is a schematical view of the hydraulic co~nand of the security device.
Figure 1 is a general schematical view of a platen press comprising a feeding station 1, a cutting station 2, a stripping station 3 and an ejection station 4 for stacking the cut sheets. The sheets to be processed in the platen press are taken up at the feeding station, transported by pincers through the cutting station 2 and stripping station 3, until they reach the ejection station 4, where the grippers release the sheets which are then stacked. The grippers 5 are mounted on bars arranged perpendicularly to the transport direction of the sheets in the platen press. Each bar is provided with pincers and linked at each end to a worm chain 6 driven by a chain wheel 7 mounted on a shaft 8. This shaft controlling the chain wheel 7 is provided with a security or overload coupling (not shown).
The security coupling is equipped with a device allowing actuation of a control circuit for emergency stopping as described in detail in Figure 7. Actuation of the control circuit operates as soon as an overload occurs in the driving of the endless chains 6.
Figure 2 is a plan view of the cutting station 2 of a platen press. To make the drawings as clear as possible, the upper plan and the silhouette of the lower platen, i.e. the movable platen 19, is shown in broken lines. The cutting station 2 comprises a driving shaft 9 with a worm 10. This driving shaft ~87~

is supported by the bearinys 11 and 12. The worm engages a worm gear 13 mounted on a shaft 14 supported by the bearings 15, 16, 17 and 18. The shaft 14 is provided with cams 20, 21, 22 and 23, on which the cams 24, 25, 26 and 27, mounted on the toggle-joints 28, 29, 30 and 31 rest. The lower movable platen 19 is pulled back downward by the pulling means 32, 33, 34 and 35. The toggle-joints 28, 29, 30 and 31 are arranged in pairs perpendicularly to the transport direction of the sheets in the machine. The toggle~joints 28 and 31 are located on a common axis, as also are the toggle-joints 29 and 30 viewed in the transport direction of the sheets in the machine, the toggle-joints 29 and 30 are positioned between the toggle-joints 28 and 31. The pulling means 32 and 34 are located between the toggle-joints 28 and 31, and the pulling means 33 and 35 are located on each side of the toggle-joints 29 and 30. On one end the driving shaft 9 is provided with a braking system.
The cutting station 2 (as seen in Figure 3) comprises a frame with a lower crosspiece 37, on which the driving means of the movable platen 19 are mounted. One of these means, i.e.
the worm, comprises a driving shaft 9 made of two half-shafts 38 and 39. The half-shaft 38, in which the worm 10 is formed is supported at one end by a bearing 12 made of a cyllndrical roller bearing 40. The other end rests on a bearing 11 made of a pair of tapered roller bearings 41 and of a ball bearing 42. The bearings 41 are mounted in a sleeve 43. This sleeve is arranged so that it can be removed from a tube 44, on which the plate 45 with the ball bearing 42 is mounted. The tube 44 is fastened against one of the faces of the lower crosspiece 37. The half-shaEt 39 is coupled to the halE-shaft 38 by internal teeth 46 engaging in external feeth 47 cut at the end of the half-shaft 38. I~he half-shaft 39 is supported on the lower crosspiece 37 by a bearing g8 having a lateral socket 49 in which a ball bearing 50 is mounted. This arrangement allows adequate align-ment of the bearings and avoids the use of a one-piece rigid shaf-t supported by four bearings. ~he half-shaft 38 is provided with a cone-shaped end 62, having a hub 63 on which a brake-disk 64 is fastened. Two jaws 65 and 66 co-operate with the brake-disk 64. These jaws are fastened by screws 68 on a bracket 67 which is connected to the lower crosspiece 37 by means of braces 69 and 70 provided with tightening screws 71.
The worm gear 13 is mounted on a shaft 14 supported by the bearings 15, 16, 17 and 18, mounted on bosses 52 in the lower crosspiece 37.
The movable platen 19 is pulled downwards by the pulling means 32, 33, 34 and 35 each including a cup 53 fastened by screws 54 on the lower crosspiece 37 and a compression spring 55. The compression spring 55 rests at one end on the bottom of the cup 53 and at the other end on a stop 56 of a rod 57.
The rod 57 is provided at its upper extremity with a union 58 equipped with a swivel 59 fastened onto the movable platen 19., The rod 57 is not closely guided in the bering 60 of the cup 53 and this allows articulation of its axis 61.
Figure 4 is a cross sectional view along the line IV-IV
of Figure 2 showing the driving system of the movable platen 19.

7~

At its lower part, this movable platen 19 is provided with four semi-cylindrical swivels 72, only two of which are shown in Figure 4. These semi-cylindrical swivels 72 are fastened on the movable platen 19 by screws 73. Each semi-cylindrical swivel acts as the upper support of a toggle-joint 28, 29, 30 and 31.
The lower support of each toggle-joint 28, 29, 30 and 31 is a cylindrical swivel 7~ fastened by a screw 75 into an arm 76 of the toggle-joint 28, 29, 30 and 31. Each toggle joint 28, 29, 30 and 31 also has an arm 77 engaging a semi-cylindrical swivel 72. The arms 76 and 77 are linked with each other by a shaft 78 bearing a cam-roller 24, 25, 26 or 27. The shaft 78 is secured to the arm 77 by the screw 79.
In order to ensure co.ntact pressure holding the cam-roller 2~, 25, 26, 27 on the surface of the cam 20, 21, 22 and 23 respectively, a compression spring is mounted outside of each toggle-joint 28, 29, 30 and 31. The compression spring 80 is attached on one end to the lower crosspiece 37 and on the other end to the lower arm 76 of each toggle-joint. The compression spring 80 is fastened to the lower crosspiece 37 by a clevis 81 provided with a pin 82 passing through the support piece 83 of the compression spring 80. A stirrup mounted on the arm 76 carries the other suppoxt piece 86 of the compression spring with the help of a pin 85.
The cylindrical swivels 74 of -the toggle-joints 28 and 31 (see Figure 2) are each seated in a halr-bearing 87 resting on a cone-shaped stop 88 mounted in the lower crosspiece 37. The cone-shaped stop 88 is selected to set the vertical positioning of the axles of the cylindrical swivels 74. This setting is ef:Eected by shifting each half-bearing 87 locking it in the cone-shaped stop by a locking system (not shown). The half-bearing 87 is guided by a slide 89 secured to the lower crosspiece 37 by screws 90.
The toggle-joints 29 and 30 rest on sylindrical swivels 74, each o~ which is seated on a half-bearing 91 mounted on a security system 165. The half-bearing 91 rests on a cone-shaped stop 93 adjustment of which occurs simi:larly to the cone-shaped stops 98 of the toggle-joints 28 and 31. The security system 165 comprises a piston rod 92 provided with a piston head 94 and located in a chamber 95 o~ a yoke 96. The piston head 94 is pressed against the face 103 of the chamber 95 by a holding pressure generated by the oil provided by the conduct 97. The face 103 of the chamber 95 has a circular groove 104 communicating with atmosphere (the air contained in the oil tank) through the tube 100. The chamber 95 is also connected to a draining device 105 (see Figure 7) :by means o:E a tube 102. The piston rod 92 comprises a piston 106 sliding in a cylinder 107 arranged in the yoke 96. The piston 106 closes a compression chamber 10 8 receiving oil under pressure from a conduct 101.
The pressure in the chamber 95 is maintained by a valve 109 leading into the chamber 95. Pressure acts on the piston 110 through the tube 99. The oil of the piloting valve is evacuated through the tube 98 towards the main tank 112 (see Figure 7).
The movable platen 19 is guided by two shoes 121 (Figure 4) mounted inside two lateral frames (not shown~. These z two shoes 121 are arranged so that they can each pivot around an axle 122. On each of its lateral faces, the movable platen 19 is provided with a slide 123 in which a shoe 121 engages.
Figure 5 is a cross sectional view on the line V-V of Figure 2 showing the toggle-joint 28 in its extended position, i.e.
when the movable platen 19 is in its upper dead centre point. The lower dead centre point of the movable platen 19 is represented by the dottedlines 113. The bearing 15, like the bearings 16, 17 and 18 (see Figure 2) is constituted by a lower clamp 114, secured on the boss 52 by means of screws 115, and by an upper clamp 116 fastened to the lower clamp 114 by screws 117. The lower clamp 114 and the upper clamp 116 hold the bushing providing the bearing.
Figure 6 is a cross sectional view on the line VI-VI of Figure 2, in which the movable platen 19 is shown in its released position, i.e. when the axis of the cylindrical swivels 74 of the toggle-joints 29 and 30 (see Figure 2) has been shifted horizontal-ly by the piston 106 from a position 119 to a position 120. This shifting effects pivoting of the movable platen 19 by an angle ~
with a respect to the vertical. The movable platen pivots around the axles 122 of the shoes 121. This pivo-ting of the movable platen 19 prevents the gripper bar 124 haviny pincers 5, located between the upper platen 125 and the movable platen 19 , from be-ing crunched in case of sudden stopping of the platen press due to the declutching of the security coupling 140. In these machines, the gripper bar in practice is frequently stopped, e.g. when jam-^
ming occurs. Stopping of the movable platen is slower than the stopping of the gripper bar, however and were the movable platen 19 ~_ g 7~(3~

to stay parallel to the upper platen 125, the cutting tool 126 could strike the gripper bar 124. This must be avoided, because the gripper bar could be badly damaged, which could lead to serious inconvenience. The pincers 5 mounted on the gripper bar 124 are formed by two jaws 166, 167 (see Figure 1) of which the gripping plane is located in the extension of the plane defined by the lower face 168 o~ the gripper bar 124.
Figure 7 is a schematical view of the hydraulic command of the security device. It shows three blocks A, B, C. Block A
reEers to the system providing the pressure, which comprises a double acting pump 127 driven by a motor 128, a distributor 129, two pressure regulators 130 and 131, two hydraulic/pneumatic accu-mulators 132 and 133, two pressostats 134 and 135 and check valves 136, 137, 138 and 139. The double acting pump 127 is made to pro-vide two different pressures, one of 150 bars and one of 50 bars.
The 150 bars pressure is to be distributed to block s and to block C, in order to be available for emergency stopping of the platen press. Emergency stopping of the platen press can result from the detection of an overload in the driving mechanism of the gripper bar 124. This overload triggers disengagement o~ the security coupling 140 and actuation of a control valve 141.
The 50 bars pressure is distributed to block C and only actuates the braking device 36 (Figure 31 when the platen press is stopped normally.
The 150 bars pressure is led to the blocks s and C
through the lines 142, 143, 144, 145 and 146. From the pump, the oil is delivered to the distributor valve 129 controlled by the pressostat 134 mounted on the line 142, then led to a pressure regulator 130 setting the pressure at 110 bars. A
check valve or non-return valve 138 is mounted on the line 146 leading simultaneously to the lines 142 and 145, and to the accumulator 132. A non-return valve 137 is mounted in the line 145. The line 142 supplies block C and line 144 block B, after their connection with the control valve 141.
The 50 bars pressure is led to the block C via lines 147 and 148, after being reduced to 40 bars by the pressure regulator 131. The pressostat 135 mounted on the line 148 controls the motor 128, so that the pressure in the line 148 is maintained between 15 and 20 bars. The line 147 provided with a non~return valve 139 entering into the line 148 and the accumulator 133.
Block B controls the disengagement device of the toggle-joints 149 (see Figure 2). This disengagement occurs in emergency stopping of the platen press, for instance because of jamming. It is initiated by release of the gripper security coupling 140. The oil pressure is delivered from block A
through the lines 99 to valves 109 (see Figure 4), which are thus kept closed. Each valve 109 controls the disengagement device 149 o-f the respective toggle-joint. The normal operating pressure is provided to each disengagement device 149 through the tubes 97 supplled by the tube 143. The chamber 95 of the disengagement device is connected with a draining device 105, comprising a valve 150 and a choke 151, through lines 102. Each di~;engagement device 149 is connected to atmosphere by means of ~87~

a valve 153 supplied by the line 100. In order to drain the oil of the annular groove or chamber 104 (see Figure 4), compressed air is blasted into the line 152 via the non-return valves 154 and 155.
The pressure oil provided by block A through the line 145 is introduced into the rear pressure chamber 108 through the line 101 connected to hy~raulic/pneumatic accumulators 156 and 157.
To ensure simultaneous stoppage of the platen press if the toggle-joints are released, the pressure existing in the lines 142 and 145 is led to block C. Line 142 supplies the valve 158 and enters into the char~er 159, whereas the line 145 enters into the chamber 160 of the valve 158. The braking system 36 is supplied with oil in order to operate in case of jamming (declutching of the security coupling 140) by the line 161 through the valve 162, and by the tube 148 for normal braking.
The line 148 goes through both valves 163 and 164. The toggle-joint release device 149 and the braking system 36 operate simultaneously in stoppage of -the platen press due to jamming.
Then, under the action o~ the valve 141, the oil in the line 142 goes back to the tank 112 and pressure is removed from the line 99. The valve 109 opens and the oil under pressure in the chambers 95 of the release devices 149 can flow back to the tank 112 through the line 98.
As soon as -the valves 109 open, the counter-pressure in the line 101 acts on the piston 106, which unseats the piston head 94 and allows the oil of chamber 95 to flow also through the ~7~

conduct 100 entering into the chamber 104. The result of this is an important acceleration in the shifting of the piston 106.
Simul-taneously, the valve 158 is opened and the oil under pressure in line 145 acts on the braking system 36, hecause the valve 162 is open at -this precise moment and the two valves 163 and 164 are closed. In normal braking of the machine, i.e. with by use of a "stop" pusher (not shown), the valve 163 and 164 are opened and let the oil under pressure from the conduct 148 flow to the actuators of the braking jaws of the braking system 36.
After a stoppage initiated by declutching of -the security coupling 140 of the platen press, upon restoration of the normal operating conditions of the platen pressl the machine can be set working again. Then, the valve 141 when reset lets oil flow into the line 148 and the chambers 95 are again under pressure, as well as the chamber 159 of the valve 158. Pressure is also re-established in lines 101 and compressed air is pulsed into chamber 104 to drain off the remaining oil. The chamber 95 is drained with the draining appliance 105, -the valve 163 is reset to drain to allow release of the braking system~ then closed to prevent the oil under pressure in line 148 from operating the braking system.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A platen press having a cutting station, and means to transport sheets through said cutting station and driving apparatus for said cutting station, said driving apparatus comprising:
a lower movable platen and an upper fixed platen, means to actuate said lower movable platen, and means transporting the sheets through the platen press, said actuating means comprising toggle-joints each having two arms hingedly connected by an axle equipped with a cam roller that is urged into engagement with a cam on a driven shaft, each toggle-joint having upper and lower swivels at the ends of its arms connected to the movable lower platen and to a stationary frame part respectively, said toggle-joints being arranged in pairs, each pair of toggle-joints being located on a theoretical axis perpendicular to the direction of forward movement of the sheets in the platen press, the lower movable platen being urged downwardly by pulling means, and said cams being effective upon rotation of said driven shaft to extend said toggle joints and move said lower platen cyclically upwards in parallel with the upper platen against the force of said pulling means, wherein each lower swivel of the forward pair of toggle-joints is connected to a stationary frame part in the form of bear-ing which is connected to a release device, said release device be-ing operable to displace said bearings away from said driven shaft and thus disable said forward pair of toggle-joints so that the up-wards movement of the forward end of the lower platen is reduced.

2. A platen press according to claim 1 wherein said driven shaft carries a worm gear which meshes with a worm carried on a driving shaft, said driving shaft having a hydraulically operated braking system associated therewith for control of the normal opera-tion of the cutting station, separate hydraulic control circuits being provided for control of said braking system and said release device, and means providing for simultaneous operation of said braking system upon actuation of the circuit that operates said release device.

3. A platen press according to claim 2 wherein said release device comprises a piston movable in a cylinder and having a piston rod connected to said bearing to move the latter in response to displacement of said piston.

4. A platen press according to claim 1, 2 or 3, wherein the pulling means comprises a compression spring pressing at one end on the bottom of a cup mounted on a lower frame member and at the other end on a stop carried on a rod connected at its upper end with the lower movable platen.

5. A platen press according to claim 2, wherein the braking system comprises two jaws acting on a brake-disk carried on said driving shaft.

6. A platen press according to claim 5, wherein the hydrau-lic control circuits of the toggle-joint release device and the braking system are adapted to be actuated simultaneously in case of an emergency stopping of the platen press by a control valve actu-ated by the release of a coupling located in the means transporting the sheets in the platen press.

7. A platen press according to claim 6, wherein the braking system is adapted to be actuated independently from the toggle-joint release device, when the platen press is stopped normally.

8. A platen press according to claim 3, wherein when said release device is non-actuated said piston obturates a chamber in said cylinder connected with a line leading to the atmosphere through a distributor.

9. A platen press according to claim 8, wherein in operation oil in said chamber is drained out by compressed air blasted into said line.

10. A platen press according to claim 3, 5 or 6, wherein in operation oil in said cylinder is released under the action of a control valve.

11. A platen press according to claim 1, 2 or 3, wherein said means to transport sheets through said cutting station comprise pincers carried by gripper bars.

12. A platen press according to claim 1, 2 or 3, wherein said means to transport sheets through said cutting station comprise pincers carried by gripper bars, said pincers having jaws with a gripping plane disposed in an extension of the lower face of the associated gripper bar.